This invention relates generally to attachment of a powered drive means to standard wheelchairs and specifically to wheelchairs that are manually operable, non-foldable or foldable and readily transportable.
Manually operable, i.e., hand propelled, wheelchairs have been manufactured for more than a century without significant change. Generally hand rings are mounted on large drive wheels to assist in propulsion by the user, although very often the actual tires are gripped by the user to propel the wheelchair. Such wheelchairs are generally satisfactory for indoor use over fairly short distances where floors are usually flat and smooth where the operator has sufficient upper body strength in at least one arm to propel the wheelchair. Operating on sloped or rough surfaces entails challenges for the person sitting in the chair. Persons with a more limited range of motion require additional provisions for driving and steering the chair. Particularly for persons paralyzed from the neck down, the problem of operating a motorized wheelchair has been great.
Various methods, generally described as human interface devices, have been proposed for allowing disabled persons, including quadriplegics, to control a motorized wheelchair. For example, breath-controlled wheelchair systems have been proposed in which a disabled person controls the chair by sucking or blowing into one or more tubes; e.g., the sip and puff system. The degree of control which can be provided is limited by the number of tubes used. Joy stick controls have been popular where direction and speed are provided by the position of a universal motion joy-stick. In the case of the disclosed apparatus, left or right joy-stick movement, for example, would control steering the wheel driver hub or hubs. Forward or back joy-stick movement would control the speed of the wheel driver hub or hubs in the forward or backward rotation.
Voice-controlled wheelchairs have also been proposed, but the variety and precision of the control they afforded has been less desirable. Furthermore, there has been a problem with commands being heard by the control system and the potential for the control system responding to a false command picked up from ambient noise, such as from the voices of people around the wheelchair.
There are other methods for controlling wheelchair movement. These are well documented in the art. Those skilled in the art will be familiar with modular or integral control systems and, in addition to those systems discussed above, will have knowledge of controls using movements of the chin, head, finger, touch pads, wafer boards, proximity switches as well as remote radio controls and/or voice commands including interfaces with mobile devices or timers controlling usage.
Outdoor operation on soft ground and up and down grades, presents additional, challenging obstacles for both users of a hand propelled wheelchair and for those users unable to provide hand propulsion who depend on powered wheelchairs with electrical controls such as joy-stick controllers.
Most powered wheelchairs and powered scooters are heavy, complicated, expensive machines. They have small, fat tires and fairly complex joy stick-operated control systems. They generally include two electric motors that may be driven by one or more large lead-acid batteries. While intended for outdoor as well as indoor use, the machines are ill-suited for unpaved surfaces like grass and dirt. Nonetheless, powered wheelchairs and scooters have been a boon to the handicapped and elderly.
Scooters generally have a single motor that drives the wheels through a differential. While the costs and weight of a differential are about the same as an extra motor and gear reduction mechanism, the controls on the scooter are less complicated and the unit is generally more reliable than a two-motor wheelchair. Steering of the front wheel of the scooter is accomplished with a small handlebar. The shopping cart is the most popular type powered scooter and, while designed primarily for indoor use, it also sees limited outdoor service in transporting both the user and groceries across a store parking lot. These vehicles' major drawbacks of cost, bulk and weight (generally in the range of 150 to 200 pounds), have prevented their widespread acceptance despite their obvious advantages. In contrast, each of the variations of the disclosed apparatus weighs approximately twenty-five pounds. Conventional powered chairs or scooters also require special measures in order to transport them. A serious drawback is that the motor drives the wheels through gearing which cannot be overdriven. Thus, a drive failure, or a dead battery, can leave the 200 pound vehicle frozen in place with its wheels effectively locked and the user helplessly stranded.
Generally, a special type van, or other vehicle providing a large door opening and specialized access equipment, is required to transport powered wheelchairs and powered scooters. The expensive vehicle is usually equipped with a power lift of some sort to enable loading and unloading of such a wheelchair.
The present invention is specifically directed to standard, manual wheelchairs. Despite the maneuverability and transportability of these manual wheelchairs, powered wheelchairs are far more capable of handling grades, soft surfaces such as grass and off road conditions. There are other devices for converting manual wheelchairs to power, but none using the single or double powered wheel/s of the present invention. The present invention set fulfills the need to enable light weight wheelchairs to be less expensively motorized and, if necessary, provide the option for joy-stick, head movement, voice control or other similar human interface devices for control without detracting from the appearance, maneuverability and transportability of the wheelchair.
The optional configurations of the disclosed invention may be both attached to a standard wheelchair and detached if desired. When detached, the disclosed apparatus is readily transportable in the trunk of a compact or larger automobile with the chair. The disclosed apparatus including the electric battery providing motive power may be attached to a standard chair in a few minutes. When attached, the powered driver hub or hubs move in parallel with the front caster wheels of the wheelchair. In the preferred embodiment of the disclosed invention, the drive mechanism consists of a wheel driver hub or hubs revealed in the U.S. Pat. No. 6,974,399 entitled, “Hub motor mechanism” and issued to Chiu-Hsiang Lo or similar apparatus. This patent describes an electrically driven hub or hubs comprising an electrical motor or motors each with a planetary gear system connected to the motor/s. Such driver hubs have the facility for regenerative braking which may be controlled by the wheelchair user employing features which may be included in one of the combinations of the disclosed set of devices. Additionally, disc brakes working in combination with regenerative braking are included the choices for configuration. A first fixed column is connected to the stator of a single electrical motor and a second fixed column is connected to a second end of the stator of a second electrical motor if the double drive is selected. Both first and/or second fixed columns are connected to the vehicle frame. A one-way clutch is connected between a cover of the driver hub/s and the planetary gear system so that the hub/s is/are rotated when the planetary gear system is activated by the motor/s powered by a battery. The rotatable castor wheels at the front of the wheelchair follow the movement of the hub/s. When the battery power is disconnected from the hub/s, the hub/s is/are free to rotate to follow the motion of the castor wheels when the wheelchair is operated in the manual mode. In an alternative embodiment to manual steering, the hub or hubs of the disclosed invention may be steered using an external motor and chain drive. This feature would enable steering by a disabled user unable to steer by hand. Either or both caster wheels may be removed from their supportive caster arms to accommodate implementation of a selected configuration of the disclosed apparatus.
The wheelchair may be operated in the manual mode even when the apparatus is attached. In this state, the wheelchair may still be easily hand propelled because of the disclosed invention's light weight and lack of bulk. When the wheel driver hub/s of the disclosed invention is/are engaged, the propelled wheelchair has excellent maneuverability and speeds greater than what can be achieved manually. Steering is accomplished in the preferred embodiment by turning the propelling wheel driver hub/s and is controlled by the user using a handlebar, or, alternatively using another means of control such as a joy-stick or other human interface device operating through servo-mechanisms. Such servo-mechanisms may include a motor drive for controlling steering. The turning radius of the wheelchair with the disclosed invention attached is approximately the same as the chair with the apparatus detached. As stated, additional controls for speed and steering may be added for those users who are unable to operate the handlebars and speed controls manually.